Deployment of endoluminal devices

ABSTRACT

A catheter assembly includes a single sleeve that constrains an expandable device to a dimension suitable for endoluminal delivery of the device to a treatment site, and further allows expansion of the device toward an outer peripheral dimension that is smaller than a fully deployed outer peripheral dimension to allow positioning of the device at the treatment site prior to full deployment and expansion of the device at the treatment site.

BACKGROUND

1. Field

The present disclosure relates to the transcatheter delivery and remotedeployment of implantable medical devices and, more particularly,implantable intraluminal devices of either the self-expanding type orthe balloon expandable type.

2. Discussion of the Related Art

Endoluminal therapies typically involve the insertion of a deliverycatheter that transports an implantable prosthetic device into thevasculature through a small, often percutaneous, access site in a remotevessel. Once access to the vasculature is achieved, the deliverycatheter is used to mediate intraluminal delivery and subsequentdeployment of the prosthesis via one of several techniques. In thisfashion, the prosthesis can be remotely implanted to achieve atherapeutic outcome. In contrast to conventional surgical therapies,endoluminal treatments are distinguished by their “minimally invasive”nature.

Expandable endoprostheses are generally comprised of a stent componentwith or without a graft covering over the stent interstices. They aredesigned to spontaneously dilate (i.e., elastically recover) or to beballoon-expanded from their delivery diameter, through a range ofintermediary diameters, up to a maximal, pre-determined functionaldiameter. The endoluminal delivery and deployment of expandableendoprostheses pose several unique problems. First, the endoprosthesisitself must be radially compacted to a suitable introductory size (ordelivery diameter) to allow insertion into the vasculature, then it mustbe constrained in that compacted state and mounted onto a deliverydevice such as a catheter shaft. Subsequently, the constraint must beremoved in order to allow the endoprosthesis to expand to its functionaldiameter and achieve the desired therapeutic outcome. A variety of waysof constraining and releasing an expandable device are known in the art.

It remains desirable to provide improved systems for endoluminaldelivery of stents or stent grafts to vascular treatment sites.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following drawings:

FIG. 1 is a side view of a catheter assembly having a compacted andconstrained medical device near a distal end of the catheter.

FIGS. 2a through 2c are partial side perspective views of an expandablemedical device shown in various stages of deployment.

FIGS. 3a through 3c, 3c ′ and 3 c″ are side views and perspective viewsdepicting a method of making a flexible constraining sleeve with tworeleasable seams.

FIGS. 4a through 4c are side views and a perspective view of a lock wirefor releasably coupling the medical device to the catheter.

DETAILED DESCRIPTION

Persons skilled in the art will readily appreciate that various aspectsof the present disclosure can be realized by any number of methods andapparatuses configured to perform the intended functions. Stateddifferently, other methods and apparatuses can be incorporated herein toperform the intended functions. It should also be noted that theaccompanying drawing figures referred to herein are not all drawn toscale, but can be exaggerated to illustrate various aspects of thepresent disclosure, and in that regard, the drawing figures should notbe construed as limiting. Finally, although the present disclosure canbe described in connection with various principles and beliefs, thepresent disclosure should not be bound by theory.

Throughout this specification and in the claims, the term “distal” canrefer to a location that is, or a portion of an intraluminal device(such as a stent-graft) that when implanted is, further downstream withrespect to blood flow than another portion of the device. Similarly, theterm “distally” can refer to the direction of blood flow or furtherdownstream in the direction of blood flow.

The term “proximal” can refer to a location that is, or a portion of anintraluminal device that when implanted is, further upstream withrespect to blood flow. Similarly, the term “proximally” can refer to thedirection opposite to the direction of blood flow or upstream from thedirection of blood flow.

With further regard to the terms proximal and distal, and because thepresent disclosure is not limited to peripheral and/or centralapproaches, this disclosure should not be narrowly construed withrespect to these terms. Rather, the devices and methods described hereincan be altered and/or adjusted relative to the anatomy of a patient.

In various embodiments, a catheter assembly is disclosed which utilizesa single flexible sleeve that releasably maintains an expandable device,such as an expandable endoluminal graft, to a dimension suitable forendoluminal delivery of the device to a treatment site, such as avascular member in a patient's body; and further limits expansion of thedevice to an outer peripheral dimension that is smaller than anunconstrained or fully deployed outer peripheral dimension therebyfacilitating selective axial and/or rotational positioning of the deviceat the treatment site prior to full deployment and expansion of thedevice toward engagement with inner walls of the vasculature at thetreatment site.

In various embodiments, for example as shown in FIG. 1, the catheterassembly, which is generally indicated at 100, includes a catheter 102,an expandable device 104 and a restraining member or flexible sleeve106. The catheter 102 extends longitudinally and has opposite proximal110 and distal 108 ends. The catheter 102 also includes a lumen 112extending between the proximal 110 and distal 108 ends.

The expandable device 104 is disposed at or near the proximal end 110 ofthe catheter 102. The device 104 is expandable to engage surroundingtissue at the treatment site, such as inner surfaces of a vascularmember. The device 104 can include a self-expanding nitinol frame thatexpands the device 104 upon deployment at the treatment site. The device104 can also be balloon expandable.

In various embodiments, the flexible sleeve 106 extends around thedevice 104 and has a first outer peripheral dimension 208, at which theflexible sleeve 106 constrains and releasably maintains the device 104in a collapsed state or small diameter delivery profile suitable forendoluminal delivery and advancement through typical vasculature to atreatment site. Fully opening the sleeve 106 allows the device 104 tofully expand toward an unconstrained or fully deployed outer peripheraldimension of the device 104, wherein the device 104 is fully expandedand not constrained by the flexible sleeve and/or vasculature. It shouldbe appreciated that the device can be oversized relative to the intendedvasculature to be treated to promote engagement between the device andthe inner walls of the vasculature at the treatment site.

The flexible sleeve can have various configurations for constraining thesleeve. In various embodiments, the sleeve 106 includes generallyopposite portions or edges each with a plurality of openings. Theopenings are arranged to form stitch lines that extend along theopposite portions of the sleeve 106. The sleeve 106 can extend aroundthe device 104 and the opposite portions brought together to form areleasable seam 206, as shown in FIG. 2a . The releasable seam 206 canbe held together by an elongated coupling member extending through orwoven through the openings. Examples of coupling members include controltethers, wires, lines, and the like. The control member can extendthrough a catheter shaft 102 and be accessed through proximal connectorsas indicated, for example, at 112, 114 or 116. Tensioning, actuation anddisplacement of the coupling member from the openings allows the sleeve106 to open along the seam 206 and the device 104 to expand toward alarger diameter. Examples of restraining members and coupling membersfor releasably maintaining expandable devices in a collapsed state forendoluminal delivery can be found in U.S. Pat. No. 6,352,561 to Leopoldet al, the content of which is incorporated herein by reference in itsentirety.

In various embodiments, the flexible sleeve 106 can be configured tomaintain the device 104 in an intermediate state, as illustrated in FIG.2b , in which the sleeve 106 is maintained at a second outer peripheraldimension that is larger than the first outer peripheral dimension ofthe sleeve 106, yet smaller than the fully deployed outer peripheraldimension of the device 104. Thus, when the device 104 is positionedgenerally at or near the treatment site, the flexible sleeve 106 can beactuated to allow the sleeve 106 to expand or be pushed outwardly towardthe intermediate state by a generally radially outward force applied byexpansion of the device 104 by, for example, a balloon and/or by a stentor wire frame portion of the device. Maintaining the device in theintermediate state allows the clinician to adjust the axial and/orrotational position of the device with respect to the vasculature priorto full release and expansion of the device toward the fully deployedouter peripheral dimension and engagement with surrounding vasculaturetissue.

In various embodiments, the sleeve is maintained in this intermediatestate or second outer peripheral dimension 204 by a second releasableseam 202 held together by a portion of the same coupling member used tosecure the first releasable seam or, alternatively, by a separatecoupling member separate from the first releasable seam. Thus, invarious embodiments, a single flexible sleeve is formed having amulti-stage deployment. In a dual stage configuration, for example, thesleeve can have a first outer peripheral dimension, indicated at 208 inFIG. 2a , releasably maintained by a first releasable seam 206 and asecond outer peripheral dimension, indicated at 204 in FIG. 2b ,releasably maintained by a second releasable seam 202. In various otherembodiments, the sleeve can be formed with more than two states orstages and associated multiple outer peripheral dimensions can beutilized leading toward the final fully deployed outer peripheraldimension by incorporating additional releasable seam arrangements.

A method of forming a restraining member in accordance with the presentdisclosure is generally illustrated by the sequence of FIGS. 3a through3c , in which a restraining member have a multi-stage deployment isformed by interconnecting portions of a flexible sheet together to forma releasable seam to define a lumen with a first outer peripheraldimension and interconnecting other portions of the flexible sheettogether to form another releasable seam to reduce the size of the lumento a second outer peripheral dimension. Shown in FIG. 3a is an edge viewof a flexible sheet material 200 that will be subsequently formed into arestraining member. In various embodiments, the sheet can be formed byflattening a tube of flexible material, such as ePTFE, so that theresulting lumen is double-walled.

The sheet 200 is folded over onto itself to form a lumen, as shown inFIG. 3b . Portions or edges of the folded sheet 200 are then stitchedwith a coupling member to form a releasable seam 202. The resultinglumen limits expansion of the device to the intermediate state, asdiscussed above.

Other portions of the flexible sheet are then folded and interconnectedto form an additional releasable seam 206 to further reduce the size ofthe lumen to an outer peripheral dimension suitable for endoluminaldelivery of the device. The cross sectional area 210 roughly illustratesthe area in which the device will be constrained.

The seams 202, 206, as shown in the illustrated embodiment in FIG. 3C,are generally radially aligned or positioned substantially along thesame side of the area 210. In various other embodiments, however, theseams can be offset rotationally about the area 210. The seams, forexample, can be disposed on opposite sides of the area 210 relative toeach other.

To reiterate the delivery sequence, the device (FIG. 1, 104) isinitially constrained to a small diameter delivery state as shown inFIG. 2a . The flexible sleeve 106, while in this small diameter state,has a small or first outer peripheral dimension 208 suitable forendoluminal delivery of the device to a treatment site. When thereleasable first seam 206 is actuated, the sleeve 106 will expand to alarger diameter state or second outer peripheral dimension 204, as shownin FIG. 2b , due to a generally radially outward force applied by theexpansion of the device 104, either by balloon and/or by a stent or wireframe portion of the device. To complete delivery or full deployment ofthe device at the treatment site, the releasable second seam 202 isactuated which “splits open” the sleeve 106 to allow the device toexpand toward the fully deployed outer peripheral dimension and engagesurrounding tissue at the treatment site.

In various embodiments, a flexible sleeve used for a constraint cancomprise materials similar to those used to form a graft. In variousother embodiments, the precursor flexible sheet (FIG. 2a , 200) can beformed from a flattened, thin wall tube. A thin wall tube (as well as asheet) can incorporate “rip-stops” in the form of longitudinal highstrength fibers attached or embedded into the sheet or tube wall.

To allow manipulation and repositioning of the partially expanded devicevia a catheter, the device, in various embodiments, is releasablycoupled to the catheter. In various embodiments, a partially or fullyexpanded stent or stent graft may be releasably coupled to a catheterby, for example, removable tie-lines, clips and the like.

In other embodiments, as shown in FIGS. 4a and 4c , a catheter shaft 400having generally opposite distal 404 and proximal ends 406 is positionedadjacent a stent graft wall 412, either internally or externally withrespect to the stent graft. To releasably couple the catheter shaft 400to the stent graft wall 412, an elongated member 402, such as a wire,can extend through a distal end 404 of the catheter shaft 400. Theelongated member 402 can further extend through the catheter lumen andextend outwardly through a distal side wall opening 408. The elongatedmember can form a loop, penetrating the graft wall 412 through at leastone aperture 413 in the graft wall 412 and returning into the catheterlumen through a proximal side wall opening 410. The elongated member 402is, by this arrangement, releasably coupled to the graft wall, allowingmanipulation and repositioning of the graft as required. Alternatively,the elongated member can extend through an apice of a wire frame or atleast extend around a portion of the wire frame to releasably couple thecatheter shaft to the stent graft wall.

When the graft is positioned at a desired location along the treatmentsite, the catheter 400 can be disengaged from the graft wall 412 toallow removal of the catheter from the treatment site and allow thestent graft to remain in place at the treatment site. More specifically,as shown in FIG. 4b , the catheter can be released from the graft wallby retracting the elongated member 402 in a distal direction as depictedby direction arrow 414. The elongated member can exit both catheter sidewall holes 408, 410 and be fully withdrawn from the catheter lumen.

An elongated member 402, as shown in FIG. 4b , can be threaded through agraft wall, through a stent frame or through a graft/stent couplingelement such as a hook. In various embodiments, elongated members canalso be attached to a graft through a “cork-screw” configuration. Such acork-screw can be twisted to engage and penetrate a graft wall (or lockto a stent frame) and be un-twisted to release the elongated member fromthe graft/stent.

Elongated members or lock wires, in various embodiments, can be formedfrom metallic, polymeric or natural materials and can compriseconventional medical grade materials such as nylon, polyacrylamide,polycarbonate, polyethylene, polyformaldehyde, polymethylmethacrylate,polypropylene, polytetrafluoroethylene, polytrifluorochlorethylene,polyvinylchloride, polyurethane, elastomeric organosilicon polymers;metals such as stainless steels, cobalt-chromium alloys and nitinol. Inother various embodiments, elongated members or lock wires can also beformed from high strength polymer fibers such as ultra high molecularweight polyethylene fibers (e.g., Spectra®, Dyneema Purity®, etc.) oraramid fibers (e.g., Technora®, etc.).

When the graft is positioned at a desired location along the treatmentsite, the flexible sleeve 106 can be further actuated to allow thesleeve 106 to “split open” and fully release the device 104, asillustrated in FIG. 2c . The device 104 can then expand toward the fullydeployed outer peripheral dimension and engage the vascular wall.Referring back to FIG. 4b , the catheter can be released from the graftwall of the now-deployed device 104 by retracting the elongated member402 in a distal direction as depicted by direction arrow 414. Theelongated member can exit both catheter side wall holes 408, 410 and befully withdrawn from the catheter lumen.

Stents can have various configurations as known in the art and can befabricated, for example, from cut tubes, wound wires (or ribbons) orflat patterned sheets rolled into a tubular form. Stents can be formedfrom metallic, polymeric or natural materials and can compriseconventional medical grade materials such as nylon, polyacrylamide,polycarbonate, polyethylene, polyformaldehyde, polymethylmethacrylate,polypropylene, polytetrafluoroethylene, polytrifluorochlorethylene,polyvinylchloride, polyurethane, elastomeric organosilicon polymers;metals such as stainless steels, cobalt-chromium alloys and nitinol andbiologically derived materials such as bovine arteries/veins,pericardium and collagen. Stents can also comprise bioresorbablematerials such as poly(amino acids), poly(anhydrides),poly(caprolactones), poly(lactic/glycolic acid) polymers,poly(hydroxybutyrates) and poly(orthoesters).

Potential materials for a graft member include, for example, expandedpolytetrafluoroethylene (ePTFE), polyester, polyurethane,fluoropolymers, such as perfouorelastomers and the like,polytetrafluoroethylene, silicones, urethanes, ultra high molecularweight polyethylene, aramid fibers, and combinations thereof. Onepreferred embodiment for a graft material is ePTFE. Other embodimentsfor a graft member material can include high strength polymer fiberssuch as ultra high molecular weight polyethylene fibers (e.g., Spectra®,Dyneema Purity®, etc.) or aramid fibers (e.g., Technora®, etc.). Thegraft member can include a bioactive agent. In one embodiment, an ePTFEgraft includes a carbon component along a blood contacting surfacethereof.

Typical materials used to construct catheters can comprise commonlyknown materials such as Amorphous Commodity Thermoplastics that includePolymethyl Methacrylate (PMMA or Acrylic), Polystyrene (PS),Acrylonitrile Butadiene Styrene (ABS), Polyvinyl Chloride (PVC),Modified Polyethylene Terephthalate Glycol (PETG), Cellulose AcetateButyrate (CAB); Semi-Crystalline Commodity Plastics that includePolyethylene (PE), High Density Polyethylene (HDPE), Low DensityPolyethylene (LDPE or LLDPE), Polypropylene (PP), Polymethylpentene(PMP); Amorphous Engineering Thermoplastics that include Polycarbonate(PC), Polyphenylene Oxide (PPO), Modified Polyphenylene Oxide (Mod PPO),Polyphenelyne Ether (PPE), Modified Polyphenelyne Ether (Mod PPE),Thermoplastic Polyurethane (TPU); Semi-Crystalline EngineeringThermoplastics that include Polyamide (PA or Nylon), Polyoxymethylene(POM or Acetal), Polyethylene Terephthalate (PET, ThermoplasticPolyester), Polybutylene Terephthalate (PBT, Thermoplastic Polyester),Ultra High Molecular Weight Polyethylene (UHMW-PE); High PerformanceThermoplastics that include Polyimide (PI, Imidized Plastic), PolyamideImide (PAI, Imidized Plastic), Polybenzimidazole (PBI, ImidizedPlastic); Amorphous High Performance Thermoplastics that includePolysulfone (PSU), Polyetherimide (PEI), Polyether Sulfone (PES),Polyaryl Sulfone (PAS); Semi-Crystalline High Performance Thermoplasticsthat include Polyphenylene Sulfide (PPS), Polyetheretherketone (PEEK);and Semi-Crystalline High Performance Thermoplastics, Fluoropolymersthat include Fluorinated Ethylene Propylene (FEP), EthyleneChlorotrifluroethylene (ECTFE), Ethylene, Ethylene Tetrafluoroethylene(ETFE), Polychlortrifluoroethylene (PCTFE), Polytetrafluoroethylene(PTFE), Polyvinylidene Fluoride (PVDF), Perfluoroalkoxy (PFA). Othercommonly known medical grade materials include elastomeric organosiliconpolymers, polyether block amide or thermoplastic copolyether (PEBAX) andmetals such as stainless steel and nickel/titanium alloys.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A catheter assembly comprising: a catheter havingopposite proximal and distal ends, the catheter having a lumen extendingbetween the proximal and distal ends of the catheter; an expandabledevice disposed at the distal end of the catheter and expandable towarda fully deployed outer peripheral dimension, the expandable devicehaving a first end and an opposite second end, the expandable devicehaving an outer surface and an opposite inner surface defining a flowlumen extending between the first end and second end; and a flexiblesleeve extending around the outer surface of the expandable device,wherein the flexible sleeve has a first releasable seam that maintainsthe flexible sleeve at a first dimension suitable for endoluminaldelivery of the expandable device to a treatment site, and a secondreleasable seam, disposed between the catheter and the first releasableseam and radially aligned therewith, that maintains the flexible sleeveat a second dimension larger than the first dimension and smaller thanthe fully deployed outer peripheral dimension to allow blood flowthrough the flow lumen during positioning of the expandable device afterrelease of the first releasable seam and prior to release of the secondreleasable seam.
 2. The catheter assembly as set forth in claim 1,wherein at least one of the first releasable seam and the secondreleasable seams is releasably held together by a coupling member. 3.The catheter assembly as set forth in claim 2, wherein the firstreleasable seam and the second releasable seams are releasably heldtogether by a common coupling member.
 4. The catheter assembly as setforth in claim 2, wherein a substantial portion of an inner surface ofthe flexible sleeve remains in contact with the expandable device beforeand after actuation of the coupling member.
 5. The catheter assembly asset forth in claim 2, wherein the expandable device remains constrainedby the flexible sleeve both before and after actuation of the couplingmember.
 6. The catheter assembly as set forth in claim 1, wherein thefirst releasable seam and the second releasable seam are generallyradially aligned with respect to a longitudinal axis of the catheter. 7.The catheter assembly as set forth in claim 6, wherein the secondreleasable seam is disposed between the longitudinal axis of thecatheter and the first releasable seam.
 8. The catheter assembly as setforth in claim 7, wherein the flexible sleeve is formed from a flattenedtube to form a double-walled lumen extending about the expandabledevice.
 9. The catheter assembly as set forth in claim 8, wherein theflattened tube is formed from ePTFE.
 10. The catheter assembly as setforth in claim 1, wherein the flexible sleeve maintains the expandabledevice at the second dimension between the first and second ends of theexpandable device after release of the first releasable seam.
 11. Acatheter assembly comprising: a catheter having opposite proximal anddistal ends, the catheter having a lumen extending between the proximaland distal ends of the catheter; an expandable device releasably coupledto the catheter and expandable toward a fully deployed outer peripheraldimension, the expandable device having a first end and an oppositesecond end, the expandable device having an outer surface and anopposite inner surface defining a flow lumen extending between the firstend and second end; a flexible sleeve extending around the outer surfaceof the expandable device, the flexible sleeve having a first releasableseam that maintains the flexible sleeve at a first outer peripheraldimension suitable for endoluminal delivery and deployment of theexpandable device to a treatment site, and a second releasable seam,disposed between the catheter and the first releasable seam and radiallyaligned therewith, that limits expansion of the flexible sleeve to asecond outer peripheral dimension between the first and second ends ofthe expandable device, the second outer peripheral dimension beinglarger than the first outer peripheral dimension and smaller than thefully deployed outer peripheral dimension after release of the firstreleasable seam to allow blood flow through the flow lumen duringpositioning of the expandable device after release of the firstreleasable seam and prior to release of the second releasable seam. 12.The catheter assembly as set forth in claim 11 including at least aportion of an elongated member extending through the catheter lumen andbeing movable relative to the catheter.
 13. The catheter assembly as setforth in claim 12, wherein a portion of the elongated member exits thecatheter lumen through a distal side wall opening so as to extend alongan outside surface of the catheter, and enters the catheter lumenthrough a proximal side wall opening.
 14. The catheter assembly as setforth in claim 13, wherein the portion of the elongated member engagesthe expandable device between the distal side wall opening and theproximal side wall openings thereby releasably coupling the expandabledevice and the catheter.
 15. The catheter assembly as set forth in claim14, wherein the expandable device includes a stent frame and the portionof the elongated member engages the stent frame thereby releasablycoupling the expandable device and the catheter.
 16. The catheterassembly as set forth in claim 15, wherein the portion of the elongatedmember extends between an apice of the stent frame and a graft wallthereby releasably coupling the expandable device and the catheter.